The universal jobmatch thing is sounding like a nightmare. From what I understand/remember at the moment it's not mandatory, but it will become so at some point.
Somehow every job is going to be listed here so they can keep track of what people are doing and stop them from lying. Check you've done the applications you've said etc.
Also will make you apply for jobs that match your skill set, and you have to accept a job you've been offered, which could see tradespeople / skilled positions being offered for less than the going rate and people being forced to accept or no benefits.
I don't get how they reckon every job will be on there though, that won't be possible, aside from unadvertised jobs, will stuff like the TUC, jobs.ac.uk or arts job mailing lists get incorporated? Will they accept these things once universal jobmatch is running or will you be required to do a certain amount through their system?
If it's going to be done online they'll be able to track exactly what pages you look at, for how long etc.. it'll become harder to game the system (though not impossible by any means and perhaps some friendly hacktivists will write a robot that people can leave to look through the universal jobmatch site and pretend to be a real person..
The issue with this is that under universal credit you're going to be required to do 30 hours/wk of jobsearch (iirc, maybe 35). Now that's pretty difficult to do every week.. unless you "volunteer".
You'll be able to volunteer for 16 hours / week and this will count towards your jobsearch requirements. Don't make your 30 hours/week and you'll get sanctioned. Don't volunteer and you'll find it hard to make your 30 hours.
Workfare.. but more voluntary than it is now. Still effectively mandatory, still effectively meaning you'll get sanctioned if you don't volunteer (through the job centre obviously, which may mean going to private companies if a work placement there would be more suitable to helping someone to gain the experience they need to find work). But technically voluntary.
Anyway, I'd be planning to spend time finding job lists/boards that are not part of universal job match and claiming I'd read through lots of person specs just to check because I wasn't sure from the job title...
caveat: all this is still kind of up in the air as UC rules are not exactly clear at the moment. The scenario above hasn't been clarified enough to know if it's true.. and hopefuly UC is going to fail due to IT anyway.